The present invention relates generally to continuous operation, industrial rotary cookers and/or sterilizers, referred to herein collectively as “rotary cookers.” More particularly, as described below, the present invention provides a rotary cooker capable of processing chamfered, stackable cans with little or no risk of can damage, leading to corrosion and contamination of contents which may otherwise occur with prior art rotary cookers. Continuous rotary cookers have been widely used for at least 45 years and are often used for cooking cans filled with food products. Over the years, the shape of the cans used in rotary cookers has been relatively standard—a single cylinder with outwardly projecting seams around the upper and lower edges. Over the past several years, a chamfered stackable can design has become increasingly popular due to its ease and efficiency of storage and handling.
However, a potentially serious problem arose when rotary cookers utilizing a prior art flat rail or track were utilized to process the newer, chamfered cans. When the modern style of chamfered tin can is moved along a prior art flat track, a part of the side wall of the can frequently contacts and frictionally engages the track. The frictional engagement and rubbing of the side wall of the can against the track may pierce or abrade the relatively thin protective coating on the exterior of the can. Once the protective coating has been pierced, the tin can may corrode, the contents may become contaminated and result in serious health hazards for consumers and liability issues for the canning and food companies involved.
The prior art has utilized several approaches in an attempt to avoid or minimize the above-described risk of corrosion and contamination. One approach is to use lubricants to try to protect the chamfered cans. Such lubricants are expensive, difficult to apply and may complicate the labeling of cans with lubricant on the surface of the cans. Another approach in the prior art is to perform batch cooking and/or sterilizing of cans. However, the batch cooking technique is much more labor intensive and less reliable than a continuous rotary cooker. More labor is required, because the cans must be loaded and unloaded from a batch cooker individually, whereas in a continuous rotary cooker the cans are automatically fed into and removed from the cooker. Another possible remedy considered by the prior art is to utilize either heavier gauge cans or thicker protective coatings, both of which would significantly increase the cost of the finished product. A further possible remedy considered in the prior art is the use of inspection techniques to identify scratched or abraded cans. Such techniques, whether manual or automatic, are extremely expensive. Applicant is unaware of any cost effective, reliable inspection techniques for this purpose.
The present invention completely overcomes the problem of the flat rail of rotary cookers damaging the protective surface of newer style chamfered cans. The present invention provides a rotary cooker rail having a design which inherently avoids frictional engagement between the rail and the side wall of the can, whether the can is a new style chamfered can or an old style can having outwardly projecting seams along their top and bottom edges. The present invention allows the newer chamfered cans to be used safely in a continuously operating rotary cooker without requiring the use of heavier gauge cans or thicker protective coatings on the cans. The improved cooker rail may be retrofitted into some of the existing rotary cookers in use. The present invention also makes it unnecessary to utilize batch cooking equipment when cooking or sterilizing products in the newer style chamfered cans.
It is therefore a primary object of the present invention to provide an improved rotary cooker utilizing a novel rail design which essentially eliminates the problem of damage caused to the side wall of chamfered cans by frictional engagement with the rotary cooker rail.
Another object of the invention is to provide an improved rotary cooker rail which allows continuous rotary cookers to process either the more modern style chamfered can or the older style cylindrical can without any significant risk of damaging the side wall of the can by frictional engagement with the cooker rail.
A further object of the invention is to avoid the necessity of utilizing a batch process cooking technique for the cooking or sterilizing of products in the newer style chamfered tin cans.
A further object of the invention is to facilitate the use of a continuous rotary cooker for processing chamfered and stackable tin cans without requiring a significant increase in the thickness of the side wall of the can or in the thickness of the protective coating on the exterior surface of the can.
Further objects and advantages of the invention will become apparent from the following description and drawings wherein: